Separation method, separation apparatus, and separation system

ABSTRACT

A method includes: a first step of disposing the superposed substrate at a position where the superposed substrate is not in contact with a first holding unit and a second holding unit in a space between the first holding unit and the second holding unit, and supplying an inert gas into the space; a second step of thereafter relatively moving the first holding unit and the second holding unit in the vertical direction, and holding the processing target substrate by the first holding unit and holding the supporting substrate by the second holding unit; and a third step of thereafter relatively moving the first holding unit and the second holding unit in the horizontal direction while heating the processing target substrate held by the first holding unit and the supporting substrate held by the second holding unit, to separate the processing target substrate and the supporting substrate from each other.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a separation method for separating asuperposed substrate into a processing target substrate and a supportingsubstrate, a separation apparatus for performing the separation method,and a separation system including the separation apparatus.

2. Description of the Related Art

In recent years, for example, in a manufacturing process of asemiconductor device, the diameter of a semiconductor wafer(hereinafter, referred to as a “wafer”) increasingly becomes larger.Further, the wafer is required to be thinner in a specific process suchas mounting. When a thin wafer with a large diameter is transferred orsubjected to polishing as it is, warpage or break can occur in thewafer. Therefore, in order to reinforce the wafer, for example, bondingthe wafer to a wafer being a supporting substrate or a glass substrateis performed. The predetermined processing such as polishing and thelike are performed on the wafer with the wafer being joined with thesupporting substrate as described above, and then the wafer and thesupporting substrate are separated from each other.

The separation of the wafer and the supporting substrate from each otheris performed using, for example, a separation apparatus. For example,Patent Document 1 proposes a separation apparatus that directly joins awafer having devices formed thereon to a supporting substrate having athermally oxidized film formed thereon and then separating the wafer.The separation apparatus has, for example, a first holder that holds thewafer, a second holder that holds the supporting substrate, and a nozzlethat jets liquid between the wafer and the supporting substrate. Then,this separation apparatus separates the wafer and the supportingsubstrate from each other by jetting liquid from the nozzle to betweenthe wafer and supporting substrate joined together, namely, to a jointsurface between the wafer and supporting substrate, at a jettingpressure greater than the joint strength between the wafer and thesupporting substrate, preferably, a jetting pressure twice or greaterthan the joint strength.

Patent Document 1: Japanese Laid-open Patent Publication No. H9-167724.

SUMMARY OF THE INVENTION

Incidentally, for joining the wafer and the supporting substrate, thereare methods of joining the wafer and the supporting substrate with anadhesive intervening between them, in addition to the method of directlyjoining the wafer to the supporting substrate having the thermallyoxidized film formed thereon as disclosed, for example, in PatentDocument 1.

In the case where the joint is performed using an adhesive, the adhesiveintervening between the wafer and the supporting substrate needs to besoftened for separating the wafer and the supporting substrate from eachother. Therefore, at the time to separate the wafer and the supportingsubstrate from each other, heat treatment is performed on the wafer andthe supporting substrate in the joined state in order to soften theadhesive.

However, if the wafer has been subjected to the heat treatment,oxidation of an exposed surface of the wafer, namely, exposed devices onthe wafer proceeds. Then, the oxidation may seriously damage products.

The present invention has been made in consideration of the above point,and an object thereof is to suppress oxidation of a surface of aprocessing target substrate during separation processing of theprocessing target substrate and a supporting substrate involving heattreatment.

To achieve the above object, the present invention is a separationmethod of separating a superposed substrate in which a processing targetsubstrate and a supporting substrate are joined together with anadhesive, into the processing target substrate and the supportingsubstrate using a separation apparatus, the separation apparatusincluding: a first holding unit that includes a heating mechanism forheating the processing target substrate and holds the processing targetsubstrate; a second holding unit that includes a heating mechanism forheating the supporting substrate and holds the supporting substrate; araising and lowering mechanism that raises and lowers the superposedsubstrate in a vertical direction between the first holding unit and thesecond holding unit; a moving mechanism that relatively moves at leastthe first holding unit or the second holding unit in a verticaldirection and a horizontal direction; and a gas supply part thatsupplies an inert gas into a space between the first holding unit andthe second holding unit, the separation method including: a first stepof disposing the superposed substrate by the raising and loweringmechanism at a position where the superposed substrate is not in contactwith the first holding unit and the second holding unit in the spacebetween the first holding unit and the second holding unit, andsupplying the inert gas from the gas supply part into the space; asecond step of thereafter relatively moving the first holding unit andthe second holding unit in the vertical direction by the movingmechanism, and holding the processing target substrate by the firstholding unit and holding the supporting substrate by the second holdingunit; and a third step of thereafter relatively moving the first holdingunit and the second holding unit in the horizontal direction by themoving mechanism while heating the processing target substrate held bythe first holding unit and the supporting substrate held by the secondholding unit, to separate the processing target substrate and thesupporting substrate from each other.

According to the present invention, the inert gas is supplied into thespace between the first holding unit and the second holding unit in thefirst step, thereby making it possible to fill the inside of the spacewith the inert gas to bring an atmosphere inside the space to a lowoxygen concentration after a lapse of a predetermined period. Inaddition, since the superposed substrate is disposed at a position wherethe superposed substrate is not in contact with the first holding unitand the second holding unit in the first step, the superposed substrate,namely, the processing target substrate is never heated. This makes itpossible to suppress the oxidation of a surface of a processing targetsubstrate in the first step. Further, the oxygen concentration in theprocessing atmosphere can be maintained at a low concentration also whenthe separation processing of the processing target substrate and thesupporting substrate is performed in the subsequent second step andthird step. Consequently, oxidation of the surface of the processingtarget substrate which has been subjected to heat treatment can also besuppressed.

The present invention according to another aspect is a separationapparatus for separating a superposed substrate in which a processingtarget substrate and a supporting substrate are joined together with anadhesive, into the processing target substrate and the supportingsubstrate, the separation apparatus including: a first holding unit thatincludes a heating mechanism for heating the processing target substrateand holds the processing target substrate; a second holding unit thatincludes a heating mechanism for heating the supporting substrate andholds the supporting substrate; a raising and lowering mechanism thatraises and lowers the superposed substrate in a vertical directionbetween the first holding unit and the second holding unit; a movingmechanism that relatively moves at least the first holding unit or thesecond holding unit in a vertical direction and a horizontal direction;a gas supply part that supplies an inert gas into a space between thefirst holding unit and the second holding unit; and a control unit thatcontrols the raising and lowering mechanism, the moving mechanism, andthe gas supply part to execute: a first step of disposing the superposedsubstrate by the raising and lowering mechanism at a position where thesuperposed substrate is not in contact with the first holding unit andthe second holding unit in the space between the first holding unit andthe second holding unit, and supplying the inert gas from the gas supplypart into the space; a second step of thereafter relatively moving thefirst holding unit and the second holding unit in the vertical directionby the moving mechanism, and holding the processing target substrate bythe first holding unit and holding the supporting substrate by thesecond holding unit; and a third step of thereafter relatively movingthe first holding unit and the second holding unit in the horizontaldirection by the moving mechanism while heating the processing targetsubstrate held by the first holding unit and the supporting substrateheld by the second holding unit, to separate the processing targetsubstrate and the supporting substrate from each other.

The present invention according to still another aspect is a separationsystem including a separation apparatus for separating a superposedsubstrate in which a processing target substrate and a supportingsubstrate are joined together with an adhesive, into the processingtarget substrate and the supporting substrate, the separation apparatusincluding: a first holding unit that includes a heating mechanism forheating the processing target substrate and holds the processing targetsubstrate; a second holding unit that includes a heating mechanism forheating the supporting substrate and holds the supporting substrate; araising and lowering mechanism that raises and lowers the superposedsubstrate in a vertical direction between the first holding unit and thesecond holding unit; a moving mechanism that relatively moves at leastthe first holding unit or the second holding unit in a verticaldirection and a horizontal direction; a gas supply part that supplies aninert gas into a space between the first holding unit and the secondholding unit; and a control unit that controls the raising and loweringmechanism, the moving mechanism, and the gas supply part to execute: afirst step of disposing the superposed substrate by the raising andlowering mechanism at a position where the superposed substrate is notin contact with the first holding unit and the second holding unit inthe space between the first holding unit and the second holding unit,and supplying the inert gas from the gas supply part into the space; asecond step of thereafter relatively moving the first holding unit andthe second holding unit in the vertical direction by the movingmechanism, and holding the processing target substrate by the firstholding unit and holding the supporting substrate by the second holdingunit; and a third step of thereafter relatively moving the first holdingunit and the second holding unit in the horizontal direction by themoving mechanism while heating the processing target substrate held bythe first holding unit and the supporting substrate held by the secondholding unit, to separate the processing target substrate and thesupporting substrate from each other, the separation system including atransfer apparatus that transfers the processing target substrateseparated in the separation apparatus, wherein the transfer apparatushas a Bernoulli chuck for jetting an inert gas to hold the processingtarget substrate, and wherein the control unit controls, after the thirdstep, the Bernoulli chuck to execute a fourth step of cooling theprocessing target substrate delivered from the first holding unit to theBernoulli chuck by supplying the inert gas from the Bernoulli chuck tothe processing target substrate.

According to the present invention, it is possible to suppress oxidationof a surface of a processing target substrate during separationprocessing of the processing target substrate and a supporting substrateinvolving heat treatment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view illustrating the outline of a configuration of aseparation system according to an embodiment;

FIG. 2 is a side view of a processing target wafer and a supportingwafer;

FIG. 3 is a longitudinal sectional view illustrating the outline of aconfiguration of a separation apparatus;

FIG. 4 is a longitudinal sectional view illustrating the outline of aninternal configuration of the separation apparatus;

FIG. 5 is a longitudinal sectional view illustrating the outline ofconfigurations of the outer peripheral portion of a first holding unitand a porous ring;

FIG. 6 is a plan view illustrating the outline of configurations of thefirst holding unit and the porous ring;

FIG. 7 is a plan view illustrating the outline of a configuration of aporous plate;

FIG. 8 is a longitudinal sectional view illustrating the outline of aconfiguration of a mechanism for supplying an inert gas to the porousplate;

FIG. 9 is a perspective view illustrating the outline of configurationsof a first cover and a third cover;

FIG. 10 is a side view illustrating the outline of the configurations ofthe first cover and the third cover;

FIG. 11 is a perspective view illustrating the outline of aconfiguration of a second cover;

FIG. 12 is a side view illustrating the outline of the configurations ofthe first cover and the second cover;

FIG. 13 is a longitudinal sectional view illustrating the outline of aconfiguration of a first cleaning apparatus;

FIG. 14 is a transverse sectional view illustrating the outline of theconfiguration of the first cleaning apparatus;

FIG. 15 is a longitudinal sectional view illustrating the outline of aconfiguration of a second cleaning apparatus;

FIG. 16 is a side view illustrating the outline of a configuration of asecond transfer apparatus;

FIG. 17 is a plan view illustrating the outline of a configuration of aBernoulli chuck;

FIG. 18 is a flowchart illustrating main steps of separation processing;

FIG. 19 is an explanatory view illustrating the appearance in which theinert gas is supplied into a processing space with a superposed waferheld on raising and lowering pins;

FIG. 20 is an explanatory view illustrating the appearance in which thesuperposed wafer is mounted on a second holding unit;

FIG. 21 is an explanatory view illustrating the appearance in which thesuperposed wafer is mounted on the second holding unit;

FIG. 22 is an explanatory view illustrating the appearance in whichsuction from a suction pipe and supply of the inert gas from the porousring are started;

FIG. 23 is an explanatory view illustrating the appearance in which thesuperposed wafer is held by the first holding unit and the secondholding unit;

FIG. 24 is an explanatory view illustrating the appearance in which thesuperposed wafer is held by the first holding unit and the secondholding unit;

FIG. 25 is an explanatory view illustrating the appearance in which thesecond holding unit is moved in the horizontal direction;

FIG. 26 is an explanatory view illustrating the appearance in which theprocessing target wafer and the supporting wafer are separated from eachother;

FIG. 27 is an explanatory view illustrating the appearance in which theprocessing target wafer is delivered from the first holding unit to theBernoulli chuck;

FIG. 28 is an explanatory view illustrating the appearance in which theinert gas is supplied to the processing target wafer held by theBernoulli chuck;

FIG. 29 is an explanatory view illustrating the appearance in which theprocessing target wafer is delivered from the Bernoulli chuck to aporous chuck;

FIG. 30 is an explanatory view illustrating the appearance in which theprocessing target wafer and the supporting wafer are relatively moved inthe horizontal direction;

FIG. 31 is a longitudinal sectional view illustrating the outline of aninternal configuration of a separation apparatus according to anotherembodiment;

FIG. 32 is a longitudinal sectional view illustrating the outline of aconfiguration of a heating device for the inert gas;

FIG. 33 is a plan view for explaining a monitoring device for poreclogging of the porous plate; and

FIG. 34 is a longitudinal sectional view for explaining the monitoringdevice for pore clogging of the porous plate.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of the present invention will be described.FIG. 1 is a plan view illustrating the outline of a configuration of aseparation system 1 according to an embodiment.

In the separation system 1, a superposed wafer T as a superposedsubstrate in which a processing target wafer W as a processing targetsubstrate and a supporting wafer S as a supporting substrate are joinedtogether with an adhesive G as illustrated in FIG. 2 is separated intothe processing target wafer W and the supporting wafer S. Hereinafter,in the processing target wafer W, the surface to be joined with thesupporting wafer S via the adhesive G is referred to as a “joint surfaceW_(J)” and the surface opposite to the joint surface W_(J) is referredto as “a non-joint surface W_(N).” Similarly, in the supporting wafer S,the surface to be joined with the processing target wafer W via theadhesive G is referred to as a “joint surface S_(J)” and the surfaceopposite to the joint surface S_(J) is referred to as “a non-jointsurface S_(N).” Note that the processing target wafer W is a wafer whichwill be a product, and a plurality of devices have been formed, forexample, on the joint surface W_(J) and the non-joint surface W_(N).Further, in the processing target wafer W, for example, the non-jointsurface W_(N) has been subjected to polishing to be thinned (forexample, with a thickness of 50 μm). The supporting wafer S is a waferwhich has the same diameter as that of the processing target wafer W andsupports the processing target wafer W. Note that a case of using awafer as the supporting substrate will be described in this embodiment,but other substrates such as, for example, a glass substrate or the likemay be used.

The separation system 1 has, as illustrates in FIG. 1, a configurationin which a transfer-in/out station 2 into/from which cassettes C_(W),C_(S), C_(T) capable of housing a plurality of processing target wafersW, a plurality of supporting wafers S, and a plurality of superposedwafers T respectively are transferred from/to the outside, a separationprocessing station 3 including various processing and treatmentapparatuses that perform predetermined processing and treatment on theprocessing target wafer W, the supporting wafer S, and the superposedwafer T, and an interface station 5 that delivers the processing targetwafer W to/from a post-processing station 4 adjacent to the separationprocessing station 3, are integrally connected.

The transfer-in/out station 2 and the separation processing station 3are arranged side by side in an X-direction (a top-bottom direction inFIG. 1). Between the transfer-in/out station 2 and the separationprocessing station 3, a wafer transfer region 6 is formed. The interfacestation 5 is located on a Y-direction negative direction side (a leftdirection side in FIG. 1) of the separation processing station 3. On anX-direction positive direction side (an upper direction side in FIG. 1)of the interface station 5, an inspection apparatus 7 that inspects theprocessing target wafer W before being delivered to the post-processingstation 4 is disposed. Further, on the side opposite to the inspectionapparatus 7 across the interface station 5, namely, on an X-directionnegative direction side (a lower direction side in FIG. 1) of theinterface station 5, a post-inspection cleaning apparatus 8 that cleansthe processing target wafer W after inspection is disposed.

In the transfer-in/out station 2, a cassette mounting table 10 isprovided. On the cassette mounting table 10, a plurality of, forexample, three cassette mounting plates 11 are provided. The cassettemounting plates 11 are arranged side by side in a line in a Y-direction(a right-left direction in FIG. 1). On these cassette mounting plates11, the cassettes C_(W), C_(S), C_(T) can be mounted when the cassettesC_(W), C_(S), C_(T) are transferred in/out from/to the outside of theseparation system 1. As described above, the transfer-in/out station 2is configured to be capable of holding the plurality of processingtarget wafers W, the plurality of supporting wafers S, and the pluralityof superposed wafers T. Note that the number of cassette mounting plates11 is not limited to this embodiment but can be arbitrarily determined.Further, the plurality of superposed wafers T transferred into thetransfer-in/out station 2 have been subjected to inspection in advanceand discriminated between a superposed wafer T including a normalprocessing target wafer W and a superposed wafer T including a defectiveprocessing target wafer W.

In the wafer transfer region 6, a first transfer apparatus 20 isdisposed. The first transfer apparatus 20 has, for example, a transferarm that is movable, for example, in the vertical direction, thehorizontal directions (the X-direction, the Y-direction), and around thevertical axis. The first transfer apparatus 20 can move in the wafertransfer region 6 and transfer the processing target wafer W, thesupporting wafer S, the superposed wafer T between the transfer-in/outstation 2 and the separation processing station 3.

The separation processing station 3 has a separation apparatus 30 thatseparates the superposed wafer T into the processing target wafer W andthe supporting wafer S. On the Y-direction negative direction side (theleft direction side in FIG. 1) of the separation apparatus 30, a firstcleaning apparatus 31 that cleans the separated processing target waferW is disposed. Between the separation apparatus 30 and the firstcleaning apparatus 31, a second transfer apparatus 32 is provided.Further, on the Y-direction positive direction side (the right directionside in FIG. 1) of the separation apparatus 30, a second cleaningapparatus 33 that cleans the separated supporting wafer S is disposed.As described above, in the separation processing station 3, the firstcleaning apparatus 31, the second transfer apparatus 32, the separationapparatus 30, and the second cleaning apparatus 33 are arranged side byside in this order from the interface station 5 side.

The inspection apparatus 7 inspects the presence or absence of a residueof the adhesive G on the processing target wafer W separated by theseparation apparatus 30. Further, the post-inspection cleaning apparatus8 cleans the processing target wafer W for which the residue of theadhesive G has been confirmed in the inspection apparatus 7. Thepost-inspection cleaning apparatus 8 has a joint surface cleaning unit 8a that cleans the joint surface W_(J) of the processing target wafer W,a non-joint surface cleaning unit 8 b that cleans the non-joint surfaceW_(N) of the processing target wafer W, and a reversing unit 8 c thatvertically reverses the processing target wafer W.

In the interface station 5, a third transfer apparatus 41 which ismovable on a transfer path 40 that extends in the Y-direction isprovided. The third transfer apparatus 41 is also movable in thevertical direction and around the vertical axis (in a θ-direction), andthus can transfer the processing target wafer W between the separationprocessing station 3, the post-processing station 4, the inspectionapparatus 7, and the post-inspection cleaning apparatus 8.

Note that in the post-processing station 4, predeterminedpost-processing is performed on the processing target wafer W separatedin the separation processing station 3. As the predeterminedpost-processing, for example, processing of mounting the processingtarget wafer W, processing of performing inspection of electriccharacteristics of the devices on the processing target wafer W,processing of dicing the processing target wafer W into chips areperformed.

Next, the configuration of the above-described separation apparatus 30will be described. The separation apparatus 30 has a processingcontainer 100 that houses a plurality of instruments therein asillustrated in FIG. 3. In the side surface of the processing container100, a transfer-in/out port (not illustrated) for the processing targetwafer W, the supporting wafer S, and the superposed wafer T is formed,and an opening/closing shutter (not illustrated) is provided at thetransfer-in/out port. Note that the processing container 100 in thisembodiment is constituted of a thin plate of, for example, stainlesssteel or the like and does not seal the inside thereof. The structure ofthe processing container 100 is not limited to this embodiment but maybe, for example, an airtight container capable of hermetically closingthe inside thereof.

At the bottom surface of the processing container 100, an exhaust port101 exhausting the atmosphere in the processing container 100 is formed.An exhaust pipe 103 communicating with an exhaust apparatus 102 such as,for example, a vacuum pump is connected to the exhaust port 101.

Inside the processing container 100, a first holding unit 110 thatsuction-holds the processing target wafer W by its lower surface, and asecond holding unit 111 that mounts and holds the supporting wafer S onits upper surface are provided. As illustrated in FIG. 4, the firstholding unit 110 is provided above the second holding unit 111 anddisposed to face the second holding unit 111. In other words, inside theprocessing container 100, the separation processing is performed on thesuperposed wafer T with the processing target wafer W arranged on theupper side and the supporting wafer S arranged on the lower side.Further, a processing space 112 in which the separation processing isperformed on the superposed wafer T is formed between the first holdingunit 110 and the second holding unit 111.

For the first holding unit 110, for example, a porous chuck is used. Thefirst holding unit 110 has a main body part 120 in a flat plate shape.On the lower surface side of the main body part 120, a porous 121 beinga porous body formed with a plurality of fine pores is provided. Theporous 121 comes into contact with, for example, the non-joint surfaceW_(N) of the processing target wafer W to suction-hold the processingtarget wafer W. Further, the diameter of a holding surface 121 a of theporous 121 that holds the processing target wafer W is smaller than thediameter of the processing target wafer W. Note that as the porous 121,for example, silicon carbide is used.

Here, the reason why the diameter of the holding surface 121 a of theporous 121 is smaller than the diameter of the processing target wafer Wwill be described. As will be described later, when the processingtarget wafer W and the supporting wafer S joined together with theadhesive G are separated from each other, the superposed wafer T isheated for softening the adhesive G. In this case, the softened adhesiveG as illustrated in FIG. 5 flows around to the non-joint surface W_(N)at the edge portion of the processing target wafer W (an arrow with abroken line in FIG. 5). Hence, to prevent the adhesive G from adheringto the porous 121 and the processing target wafer W to fix theprocessing target wafer W to the porous 121, the diameter of the holdingsurface 121 a of the porous 121 is made smaller than the diameter of theprocessing target wafer W. In addition, between the outer peripheralportion of the main body part 120 of the first holding unit 110 and theouter peripheral portion of the processing target wafer W, a groove part122 is formed correspondingly to the setback arrangement of the porous121.

Further, as illustrated in FIG. 4, a flow space 123 for gas is formedinside the main body part 120 and above the porous 121. The flow space123 is formed, for example, in a manner to cover the porous 121. To theflow space 123, a suction pipe 124 as a suction part and a gas supplypipe 125 as a gas supply part are connected. The suction pipe 124 isconnected to a negative pressure generating apparatus 126 such as, forexample, a vacuum pump. Then, the non-joint surface W_(N) of theprocessing target wafer W is sucked from the suction pipe 124 via theflow space 123 and the porous 121 so that the processing target wafer Wis suction-held by the first holding unit 110. The gas supply pipe 125is connected to an inert gas supply source 127 that supplies, forexample, a nitrogen gas as an inert gas. The inert gas is supplied fromthe gas supply pipe 125 to the processing space 112 via the flow space123 and the porous 121. In this event, the inert gas is evenly suppliedfrom the entire surface of the porous 121 because the porous 121 isformed with the plurality of pores. Note that the suction of theprocessing target wafer W from the suction pipe 124 and the supply ofthe inert gas from the gas supply pipe 125 are switched over atlater-described predetermined timing. Note that the inert gas is notlimited to the nitrogen gas in this embodiment but may be any gas aslong as it contains no oxygen atom.

Further, inside the main body part 120 and above the flow space 123, aheating mechanism 128 that heats the processing target wafer W isprovided. For the heating mechanism 128, for example, a heater is used.

At the outer peripheral portion of the first holding unit 110, a porousring 130 is provided as a porous part formed with a plurality of finepores. The porous ring 130 is annularly provided along the outerperipheral portion of the first holding unit 110 as illustrated in FIG.6. Further, the porous ring 130 is arranged to face the groove part 122as illustrated in FIG. 5. An inert gas supply source 132 that supplies,for example, a nitrogen gas, as an insert gas is connected to the porousring 130 via a gas supply pipe 131. The porous ring 130 can horizontallysupply the inert gas to the outer peripheral portion of the firstholding unit 110, namely, the groove part 122. Note that as the porousring 130, for example, silicon carbide is used. Further, the inert gasis not limited to the nitrogen gas in this embodiment but may be any gasas long as it contains no oxygen atom.

On the upper surface of the first holding unit 110, a supporting plate140 that supports the first holding unit 110 is provided as illustratedin FIG. 3. The supporting plate 140 is supported on the ceiling surfaceof the processing container 100. Note that the supporting plate 140 inthis embodiment may be omitted so that the first holding unit 110 issupported in contact with the ceiling surface of the processingcontainer 100.

Inside the second holding unit 111, a suction pipe 150 forsuction-holding the supporting wafer S is provided as illustrated inFIG. 4. The suction pipe 150 is connected to a negative pressuregenerating apparatus (not illustrated) such as, for example, a vacuumpump.

Further, inside the second holding unit 111, a heating mechanism 151that heats the supporting wafer S is provided. For the heating mechanism151, for example, a heater is used.

Below the second holding unit 111, a raising and lowering mechanism 160that raises and lowers the superposed wafer T (or the supporting waferS) in the processing space 112 is provided. The raising and loweringmechanism 160 has, for example, three raising and lowering pins 161 forraising and lowering the superposed wafer T while supporting it frombelow. The raising and lowering pins 161 can move up and down by meansof a driving unit 162. The driving unit 162 has, for example, a ballscrew (not illustrated) and a motor (not illustrated) that turns theball screw. Further, near the central portion of the second holding unit111, through holes 163 penetrating the second holding unit 111 and alater-described supporting plate 173 are formed, for example, at threelocations. The raising and lowering pins 161 can be inserted into thethrough holes 163 to project from the upper surface of the secondholding unit 111.

Below the second holding unit 111, a moving mechanism 170 that moves thesecond holding unit 111 and the supporting wafer S in the verticaldirection and the horizontal direction is provided. The moving mechanism170 has a vertical moving unit 171 that moves the second holding unit111 in the vertical direction and a horizontal moving unit 172 thatmoves the second holding unit 111 in the horizontal direction.

The vertical moving unit 171 has a supporting plate 173 that supportsthe lower surface of the second holding unit 111, a driving unit 174that raises and lowers the supporting plate 173, and supporting members175 that support the supporting plate 173. The driving unit 174 has, forexample, a ball screw (not illustrated) and a motor (not illustrated)that turns the ball screw. Further, the supporting members 175 areconfigure to be capable of expansion and contraction in the verticaldirection, and provided, for example, at three locations between thesupporting plate 173 and a later-described supporting body 181.

The horizontal moving unit 172 has, as illustrated in FIG. 3, a rail 180that extends along an X-direction (a right-left direction in FIG. 3),the supporting body 181 attached to the rail 180, and a driving unit 182that moves the supporting body 181 along the rail 180. The driving unit182 has, for example, a ball screw (not illustrated) and a motor (notillustrated) that turns the ball screw.

On an X-direction positive direction side (a right side in FIG. 3) ofthe second holding unit 111, a porous plate 190 is provided as a porousplate formed with a plurality of fine pores. To the porous plate 190, agas supply pipe 191 is connected which supplies an inert gas to theporous plate 190. Further, the porous plate 190 is supported by thesupporting body 181 of the horizontal moving unit 172 via a supportingmember 192 so that the porous plate 190 can be moved in the horizontaldirection by moving the horizontal moving unit 172. In other words, theporous plate 190 moves in the horizontal direction in synchronizationwith the second holding unit 111. Further, the porous plate 190 cansupply the inert gas to the joint surface W_(J) of the processing targetwafer W exposed by moving the second holding unit 111 in the horizontaldirection by the horizontal moving unit 172. Note that as the porousplate 190, for example, silicon carbide is used.

The porous plate 190 has a flat plate shape capable of covering theprocessing target wafer W in a plan view as illustrated in FIG. 7.Further, at an end portion in the moving direction of the porous plate190 when the porous plate 190 is moved by the horizontal moving unit172, a hollow portion 190 a is formed which is hollowed in a recessshape along the shape of the processing target wafer W in a plan view.More specifically, as illustrated in FIG. 7, the end portion in themoving direction of the porous plate 190 is hollowed in a semicircularshape with a diameter substantially the same as that of the processingtarget wafer W, and the portion of the porous plate 190 other than thehollow portion 190 a has a size capable of covering the processingtarget wafer W. Further, in the porous plate 190, an end portion 190 bopposite the end portion where the hollow portion 190 a is formed, has ashape projecting in a semicircular shape with a diameter larger thanthat of the processing target wafer W. Accordingly, the porous plate 190has a minimum size for covering the processing target wafer W. Note thatthe size of the porous plate 190 is not limited to this embodiment butcan be arbitrarily set.

The porous plate 190 is provided in parallel with the joint surfaceW_(J) of the processing target wafer W as illustrated in FIG. 3 and FIG.4. Further, the porous plate 190 is arranged in a manner that the hollowportion 190 a thereof is in contact with the outer peripheral portion ofthe processing target wafer W in a plan view as illustrated in FIG. 7 ina state that the first holding unit 110 and the second holding unit 111face each other, namely, in a state that the processing target wafer Wand the supporting wafer S are joined together.

The arrangement in the vertical direction of the porous plate 190 isadjusted so that the porous plate 190 is located below the joint surfaceW_(J) of the processing target wafer W. In other words, the porous plate190 is distanced from the joint surface W_(J) of the processing targetwafer W by a predetermined distance in the vertical direction. Note thatthe predetermined distance is set to 2 mm in this embodiment.

On the lower surface of the porous plate 190, a distribution plate 193in a flat plate shape is provided in a manner to cover the porous plate190 as illustrated in FIG. 8. As the distribution plate 193, forexample, a plate made of metal such as aluminum, stainless steel isused. Inside the distribution plate 193, a gas flow passage 194 isformed. The above-described gas supply pipe 191 is connected to the gasflow passage 194 of the distribution plate 193.

The end portion of the gas supply pipe 191 opposite to the distributionplate 193 side is connected to an inert gas supply source 195 thatsupplies, for example, a nitrogen gas as the inert gas. Further, the gasflow passage 194 of the distribution plate 193 is provided in a mannerto branch into a plurality of portions from the side to which the gassupply pipe 191 is connected toward the porous plate 190 and formed tobe able to supply the inert gas evenly within a plane of the porousplate 190. Therefore, the inert gas supplied from the inert gas supplysource 195 is supplied evenly within a plane of the porous plate 190 viathe distribution plate 193. Note that the inert gas is not limited tothe nitrogen gas in this embodiment but may be any gas as long as itcontains no oxygen atom.

As illustrated in FIG. 4, the first holding unit 110 and the secondholding unit 111 are provided with a first cover 200 and a second cover201 respectively. The first cover 200 and the second cover 201 areprovided in a manner to cover the processing space 112 between the firstholding unit 110 and the second holding unit 111 as will be describedlater. The first cover 200 is further provided with a third cover 202 ina manner to cover the porous plate 190.

The first cover 200 has a flat plate part 210 and side wall parts 211 asillustrated in FIG. 9 and FIG. 10. A central portion of the flat platepart 210 is opened along the outer peripheral portion of the main bodypart 120 of the first holding unit 110, and the first cover 200 isattached to the first holding unit 110 in the opening. Further, the sidewall parts 211 extend vertically downward from the flat plate part 210and are provided along the moving direction (the X-direction in thedrawing) of the second holding unit 111 and the porous plate 190. Inother words, both end portions of the first cover 200 in the movingdirection (the X-direction in the drawing) of the second holding unit111 and the porous plate 190 are opened. Further, the side wall parts211 are provided in a manner to cover the porous 121, the groove part122, and the porous ring 130. Note that bent parts 212 horizontallyextending inward from the side wall parts 211 are provided at the endportions on the X-direction positive direction side of the side wallparts 211 as will be described later.

The second cover 201 has a flat plate part 213 and side wall parts 214as illustrated in FIG. 11. The flat plate part 213 is attached to thesecond holding unit 111 in a manner to cover almost ⅔ of the outerperipheral portion on the X-direction negative direction side of thesecond holding unit 111. In short, the flat plate part 213 is providedat a position not interfering with the porous plate 190 in a plan view.Note that at a position where the flat plate part 213 is not provided onthe X-direction positive direction side of the second holding unit 111,the aforementioned bent parts 212 of the first cover 200 are disposed.Further, the side wall parts 214 extend vertically upward from the flatplate part 213 and are provided along the moving direction (theX-direction in the drawing) of the second holding unit 111 and theporous plate 190. In other words, both end portions of the second cover201 in the moving direction (the X-direction in the drawing) of thesecond holding unit 111 and the porous plate 190 are opened.

The first cover 200 and the second cover 201 are arranged in a manner tocover the processing space 112 between the first holding unit 110 andthe second holding unit 111 as illustrated in FIG. 12. The first holdingunit 110 and the second holding unit 111 are provided, for example, suchthat the side wall parts 211 of the first holding unit 110 are locatedoutside the side wall parts 214 of the second holding unit 111.

The third cover 202 has a ceiling part 215, a side wall part 216, and abottom surface part 217 as illustrated in FIG. 9 and FIG. 10. Theceiling part 215 and the side wall part 216 are attached to the flatplate part 210 and the side wall parts 211 of the first cover 200respectively. The ceiling part 215 and the bottom surface part 217 haveflat plate shapes along the outer peripheral portion of the porous plate190. Further, the side wall part 216 is arranged to connect the ceilingpart 215 and the bottom surface part 217. As described above, the thirdcover 202 is provided in a manner to cover the porous plate 190, and awaiting space 218 for the porous plate 190 is formed inside the thirdcover 202. Further, an end portion of the third cover 202 in the movingdirection (in the X-direction negative direction) of the porous plate190 is opened. Note that the bottom surface part 217 is formed with acutout (not illustrated) to avoid interference with the gas supply pipe191 and the supporting member 192.

As described above, the first cover 200, the second cover 201, and thethird cover 202 are configured so that the second holding unit 111 andthe porous plate 190 can move in the horizontal direction. Further, asillustrated in FIG. 4, the atmosphere in the space surrounded by thefirst cover 200, the second cover 201, and the third cover 202, namely,the atmosphere in the processing space 112 and in the waiting space 218is exhausted from an opening 220 formed at the first cover 200 and thesecond cover 201 on the opposite side to the third cover 202. In short,the atmosphere in the processing space 112 and the waiting space 218flows to the X-direction negative direction side in the drawing. Notethat to actively exhaust the atmosphere in the processing space 112 andthe waiting space 218, an exhaust apparatus 221 such as a vacuum pumpmay be provided at the opening 220.

Next, the configuration of the above-described first cleaning apparatus31 will be described. The first cleaning apparatus 31 has a treatmentcontainer 230 as illustrated in FIG. 13. In a side surface of thetreatment container 230, a transfer-in/out port (not illustrated) forthe processing target wafer W is formed, and an opening/closing shutter(not illustrated) is provided at the transfer-in/out port.

At a central portion inside the treatment container 230, a porous chuck240 that holds and rotates the processing target wafer W thereon isprovided. The porous chuck 240 has a main body part 241 in a flat plateshape and a porous 242 provided on the upper surface side of the mainbody part 241 and formed with a plurality of pores. The porous 242 has,for example, substantially the same diameter as that of the processingtarget wafer W and is in contact with the non-joint surface W_(N) of theprocessing target wafer W. Note that as the porous 242, for example,silicon carbide is used. A suction pipe (not illustrated) is connectedto the porous 242 and sucks the non-joint surface W_(N) of theprocessing target wafer W from the suction pipe via the porous 242 andthereby can suction-hold the processing target wafer W on the porouschuck 240.

Below the porous chuck 240, a chuck driving unit 243 equipped with, forexample, a motor is provided. The porous chuck 240 can rotate at apredetermined speed by means of the chuck driving unit 243. Further, thechuck driving unit 243 is provided with a raising and lowering drivingsource such as, for example, a cylinder so that the porous chuck 240 canfreely rise and lower.

Around the porous chuck 240, a cup 244 is provided that receives andrecovers liquid splashing or dropping from the processing target waferW. A drain pipe 245 that drains the recovered liquid and an exhaust pipe246 that vacuums and exhausts the atmosphere inside the cup 244 areconnected to the lower surface of the cup 244.

As illustrated in FIG. 14, on an X-direction negative direction (adownward direction in FIG. 14) side of the cup 244, a rail 250 thatextends along a Y-direction (a right-left direction in FIG. 14) isformed. The rail 250 is formed, for example, from a Y-direction negativedirection (a left direction in FIG. 14) side outer position of the cup244 to a Y-direction positive direction (a right direction in FIG. 14)side outer position. On the rail 250, an arm 251 is attached.

On the arm 251, a cleaning solution nozzle 253 that supplies a cleaningsolution, for example, an organic solvent to the processing target waferW is supported as illustrated in FIG. 13 and FIG. 14. The arm 251 ismovable on the rail 250 by means of a nozzle driving unit 254illustrated in FIG. 14. Thus, the cleaning solution nozzle 253 can movefrom a waiting section 255 provided at the Y-direction positivedirection side outer position of the cup 244 to a position above acentral portion of the processing target wafer W in the cup 244, andfurther move in the diameter direction of the processing target wafer Wabove the processing target wafer W. Further, the arm 251 can freelyrise and lower by means of the nozzle driving unit 254 to be able toadjust the height of the cleaning solution nozzle 253.

For the cleaning solution nozzle 253, for example, a two-fluid nozzle isused. To the cleaning solution nozzle 253, a supply pipe 260 thatsupplies the cleaning solution to the cleaning solution nozzle 253 isconnected as illustrated in FIG. 13. The supply pipe 260 communicateswith a cleaning solution supply source 261 that stores the cleaningsolution therein. The supply pipe 260 is provided with a supplyequipment group 262 including a valve, a flow regulator and so on thatcontrol the flow of the cleaning solution. Further, to the cleaningsolution nozzle 253, a supply pipe 263 that supplies a nitrogen gas, forexample, as an inert gas to the cleaning solution nozzle 253 isconnected. The supply pipe 263 communicates with an inert gas supplysource 264 that stores the inert gas therein. The supply pipe 263 isprovided with a supply equipment group 265 including a valve, a flowregulator and so on that control the flow of the inert gas. Then, thecleaning solution and the inert gas are mixed together in the cleaningsolution nozzle 253 and supplied from the cleaning solution nozzle 253to the processing target wafer W. Note that the mixture of the cleaningsolution and the inert gas is sometimes referred to simply as a“cleaning solution” hereinafter.

Incidentally, below the porous chuck 240, raising and lowering pins (notillustrated) for supporting the processing target wafer W from below andraising and lowering it may be provided. In this case, the raising andlowering pins are configured to be able to pass through through holes(not illustrated) formed in the porous chuck 240 and project from theupper surface of the porous chuck 240. Then, in place of raising andlowering the porous chuck 240, the raising and lowering pins are raisedor lowered to deliver the processing target wafer W to/from the porouschuck 240. Note that the configurations of the above-described jointsurface cleaning unit 8 a and the non-joint surface cleaning unit 8 b ofthe above-described post-inspection cleaning apparatus 8 are the same asthose of the first cleaning apparatus 31, and therefore the descriptionof the joint surface cleaning unit 8 a and the non-joint surfacecleaning unit 8 b is omitted.

Further, the configuration of the second cleaning apparatus 33 issubstantially the same as the configuration of the above-described firstcleaning apparatus 31. In the second cleaning apparatus 33, a spin chuck270 is provided as illustrated in FIG. 15 in place of the porous chuck240 of the first cleaning apparatus 31. The spin chuck 270 has ahorizontal upper surface, and a suction port (not illustrated) forsucking, for example, the supporting wafer S is provided in the uppersurface. By suction through the suction port, the supporting wafer S canbe suction-held on the spin chuck 270. The other configuration of thesecond cleaning apparatus 33 is the same as that of the above-describedfirst cleaning apparatus 31, and therefore the description thereof isomitted.

Incidentally, in the second cleaning apparatus 33, a back rinse nozzle(not illustrated) that jets a cleaning solution toward the rear surfaceof the supporting wafer S, namely, the non-joint surface S_(N) may beprovided below the spin chuck 270. The cleaning solution jetted from theback rinse nozzle cleans the non-joint surface S_(N) of the supportingwafer S and the outer peripheral portion of the supporting wafer S.

Next, the configuration of the above-described second transfer apparatus32 will be described. The second transfer apparatus 32 has a Bernoullichuck 280 that holds the processing target wafer W as illustrated inFIG. 16. The Bernoulli chuck 280 is supported by a supporting arm 281.The supporting arm 281 is supported by a first driving unit 282. Bymeans of the first driving unit 282, the supporting arm 281 can turnaround the horizontal axis and expand and contract in the horizontaldirection. At a lower portion of the first driving unit 282, a seconddriving unit 283 is provided. By means of the second driving unit 283,the first driving unit 282 can rotate around the vertical axis and riseand lower in the vertical direction.

In the Bernoulli chuck 280, a plurality of gas jetting ports 290 forjetting, for example, a nitrogen gas, as an inert gas are arranged asillustrated in FIG. 17. In the illustrated example, the plurality of gasjetting ports 290 are arranged at regular intervals on double concentriccircles being concentric circles of the Bernoulli chuck 280. To the gasjetting ports 290, an inert gas supply source 292 that supplies theinert gas is connected via a gas supply pipe 291. The Bernoulli chuck280 jets the inert gas to float the processing target wafer W and sucksand suspends the processing target wafer W to hold it in a non-contactstate. Note that the number and arrangement of the gas jetting ports 290are not limited to this embodiment buy can be arbitrarily set.

Note that the third transfer apparatus 41 has the same configuration asthat of the above-described second transfer apparatus 32, and thereforethe description thereof is omitted. However, a second driving unit 283of the third transfer apparatus 41 is attached to the transfer path 40illustrated in FIG. 1 so that the third transfer apparatus 41 is movableon the transfer path 40.

In the above separation system 1, a control unit 300 is provided asillustrated in FIG. 1. The control unit 300 is, for example, a computerand has a program storage part (not illustrated). In the program storagepart, a program is stored which controls the processing on theprocessing target wafer W, the supporting wafer S, and the superposedwafer T in the separation system 1. Further, the program storage partalso stores a program for controlling the operation of the drivingsystem such as the above-described various processing and treatmentapparatuses and transfer apparatuses to implement the later-describedseparation processing in the separation system 1. Note that the programmay be the one that is stored, for example, in a computer-readablestorage medium H such as a computer-readable hard disk (HD), flexibledisk (FD), compact disk (CD), magneto-optical disk (MO), or memory card,and installed from the storage medium H into the control unit 300.

Next, the separation processing method of the processing target wafer Wand the supporting wafer S performed using the separation system 1configured as described above will be described. FIG. 18 is a flowchartillustrating an example of main steps of the separation processing.

First, a cassette C_(T) housing a plurality of superposed wafers T, anempty cassette C_(W), and an empty cassette C_(S) are mounted on thepredetermined cassette mounting plates 11 in the transfer-in/out station2. The superposed wafer T in the cassette C_(T) is taken out by thefirst transfer apparatus 20 and transferred to the separation apparatus30 in the separation processing station 3. In this event, the superposedwafer T is transferred with the processing target wafer W arranged onthe upper side and the supporting wafer S arranged on the lower side.

The superposed wafer T transferred in the separation apparatus 30 isdelivered to the raising and lowering pins 161 which have been raisedand waiting in advance as illustrated in FIG. 12 and FIG. 19. Then, thesecond holding unit 111 is raised by the moving mechanism 170 to apredetermined position, and the inert gas is supplied into theprocessing space 112 from the gas supply pipe 125 and the gas supplypipe 191 with the superposed wafer T held on the raising and loweringpins 161 in the processing space 112 (step A1 in FIG. 18).

In this event, the second holding unit 111 is disposed at a positionwhere, for example, the distance in the vertical direction of theprocessing space 112 is about 10 mm. Further, the superposed wafer T isin a state of being held on the raising and lowering pins 161 in theprocessing space 112, and disposed at a position where it is not incontact with any of the first holding unit 110 and the second holdingunit 111. Therefore, the superposed wafer T is never heated by theheating mechanisms 128, 151. Then, in the state that the superposedwafer T is held on the raising and lowering pins 161, the inert gas issupplied from the gas supply pipe 125 and the gas supply pipe 191. Theinert gas supplied from the gas supply pipe 125 flows through the insideof the processing space 112, namely, both sides above and below thesuperposed wafer T and is then exhausted from the opening 220. Further,the inert gas supplied from the gas supply pipe 191 via the porous plate190 also flows through the inside of the waiting space 21 and theprocessing space 112 and is then exhausted from the opening 220. Thus,the atmosphere inside the processing space 112 where the superposedwafer T is to be separated is replaced with the inert gas, and theatmosphere is maintained at a predetermined low oxygen concentration atthe ppm level.

In step A1, the volume capacity of the processing space 112 is reducedby raising the second holding unit 111, so that the atmosphere in theprocessing space 112 reaches the predetermined low oxygen concentrationin a short time. Further, the inert gas is being supplied to the insideof the processing space 112 without heating of the superposed wafer T,thereby enabling suppression of oxidation of the non-joint surface W_(N)of the processing target wafer W.

Thereafter, the raising and lowering pins 161 are lowered to mount thesuperposed wafer T on the second holding unit 111 as illustrated in FIG.20 and FIG. 21. Subsequently, the superposed wafer T is sucked from thesuction pipe 150, and the non-joint surface S_(N) of the supportingwafer S is suction-held by the second holding unit 111 (step A2 in FIG.18). In this event, the supply of the inert gas from the gas supply pipe125 and the gas supply pipe 191 to the processing space 112 iscontinued. Note that when mounting the superposed wafer T on the secondholding unit 111, the second holding unit 111 may be raised by themoving mechanism 170.

Thereafter, as illustrated in FIG. 22, the supply of the inert gas fromthe gas supply pipe 125 is stopped and the suction from the suction pipe124 is started as illustrated in FIG. 22. Further, the inert gas issupplied from the porous ring 130 to the outer peripheral portion of thefirst holding unit 110. Subsequently, as illustrated in FIG. 23 and FIG.24, the second holding unit 111 is raised by the moving mechanism 170 sothat the first holding unit 110 suction-holds the non-joint surfaceW_(N) of the processing target wafer W (step A2 in FIG. 18).

As described above, when the first holding unit 110 suction-holds theprocessing target wafer W, the inert gas is supplied from the porousring 130 to the outer peripheral portion of the first holding unit 110.In this event, the inert gas is supplied from the porous ring 130 formedwith the plurality of pores, so that the flow rate of the inert gas issuppressed. Thus, when supplying the inert gas, only the inert gas issupplied to the outer peripheral portion of the first holding unit 110without involving the surrounding air thereinto. In addition, the inertgas is supplied to the groove part 122 between the first holding unit110 and the processing target wafer W, so that the inside of the groovepart 122 is made into an atmosphere of the inert gas. Then, even ifdevices are formed on the non-joint surface W_(N) of the processingtarget wafer W, namely, even when a gap is generated between the holdingsurface 121 a of the first holding unit 110 and the non-joint surfaceW_(N) of the processing target wafer W, only the inert gas supplied fromthe porous ring 130 via the groove part 122 flows into the gap.Accordingly, the oxidation of the non-joint surface W_(N) of theprocessing target wafer W which has been subjected to heat treatment canbe suppressed.

Thereafter, the superposed wafer T is heated by the heating mechanisms128, 151 to a predetermined temperature, for example, 200° C. Thus, theadhesive G in the superposed wafer T is softened. In this event, thesupply of the inert gas from the gas supply pipe 191 is continuouslyperformed. In other words, the inert gas is supplied from the uppersurface of the porous plate 190 via the gas supply pipe 191 and thedistribution plate 193. In this event, the supply of the inert gas viathe porous plate 190 formed with the plurality of fine pores cansuppress the flow rate of the inert gas supplied from the porous plate190. Therefore, when supplying the inert gas, the surrounding air isnever involved therein. Accordingly, the atmosphere of the inert gascontaining no air can be formed on the upper surface side of the porousplate 190. Further, the gas flow passage 194 provided in a manner tobranch into a plurality of portions toward the porous plate 190 isformed inside the distribution plate 193, so that the inert gas isevenly supplied from the entire surface on the upper surface side of theporous plate 190.

Subsequently, while keeping the softened state of the adhesive G byheating the superposed wafer T, the second holding unit 111 and thesupporting wafer S are moved in the horizontal direction as illustratedin FIG. 25 by the moving mechanism 170. Further, the porous plate 190 issupported on the horizontal moving unit 172 by the supporting body 181,and therefore moved in the horizontal direction in synchronization withthe second holding unit 111 accompanying the movement of the horizontalmoving unit 172.

In this event, since the porous plate 190 is distanced from the jointsurface W_(J) of the processing target wafer W by a predetermineddistance L in the vertical direction as illustrated in FIG. 25, theporous plate 190 is moved in the horizontal direction withoutinterfering with the joint surface W_(J) of the processing target waferW. Therefore, the joint surface W_(J) of the processing target wafer Wexposed due to the movement is brought into a state of facing the porousplate 190 and distanced from the porous plate 190 by the distance L.During this time, the inert gas is supplied to the joint surface W_(J)of the processing target wafer W from the porous plate 190.

Thereafter, while the supply of the inert gas from the porous plate 190is continued, the second holding unit 111 is moved in the horizontaldirection to separate the processing target wafer W held by the firstholding unit 110 and the supporting wafer S held by the second holdingunit 111 from each other as illustrated in FIG. 26 (step A3 in FIG. 18).In this event, the inert gas from the porous plate 190 is continuouslysupplied also to the joint surface W_(J) of the processing target waferW for which the separation has been completed since the porous plate 190is formed in a size capable of covering the processing target wafer W ina plan view.

Thereafter, the processing target wafer W separated in the separationapparatus 30 is delivered from the first holding unit 110 to theBernoulli chuck 280 of the second transfer apparatus 32 as illustratedin FIG. 27. As for the delivery of the processing target wafer W, first,the supporting arm 281 is extended to disposed the Bernoulli chuck 280under the processing target wafer W held by the first holding unit 110.Thereafter, the Bernoulli chuck 280 is raised, and the suction of theprocessing target wafer W from the suction pipe 124 in the first holdingunit 110 is stopped. Then, the processing target wafer W is deliveredfrom the first holding unit 110 to the Bernoulli chuck 280. Thereafter,the Bernoulli chuck 280 is lowered to a predetermined position. Notethat the processing target wafer W is held in a non-contact state by theBernoulli chuck 280. Therefore, the processing target wafer W is heldwithout damage to the devices on the joint surface W_(J) of theprocessing target wafer W. Note that the second holding unit 111 ismoved to a position where it faces the first holding unit 110.

Thereafter, the inert gas is supplied from the gas supply pipe 125 tothe non-joint surface W_(N) of the processing target wafer W asillustrated in FIG. 28. Further, the processing target wafer W is heldby the Bernoulli chuck 280, and the inert gas is supplied from theBernoulli chuck 280 to the joint surface W_(J) of the processing targetwafer W (step A4 in FIG. 18). By supplying the inert gas to theprocessing target wafer W for a predetermined period, the processingtarget wafer W is cooled to a predetermined temperature, for example,equal to or lower than 100° C. to 150° C. Then, after the state wherethe oxidation at the joint surface W_(J) and the non-joint surface W_(N)does not proceed any longer is established, the supply of the inert gasfrom the gas supply pipe 125 is stopped.

Note that when cooling the processing target wafer W, the supply of theinert gas from the porous ring 130 may be performed continuously fromstep A3. In this case, the inert gas is supplied to the first holdingunit 110, and a part of the inert gas is supplied to the non jointsurface W_(N) of the processing target wafer W.

Thereafter, the processing target wafer W cooled to the predeterminedtemperature is transferred, while held by the Bernoulli chuck 280, tothe first cleaning apparatus 31 by the second transfer apparatus 32 asillustrated in FIG. 29. As for the transfer of the processing targetwafer W, the supporting arm 281 is turned to move the Bernoulli chuck280 to above the porous chuck 240 of the first cleaning apparatus 31,and the Bernoulli chuck 280 is reversed to face the processing targetwafer W downward. In this event, the porous chuck 240 has been raised toabove the cup 244 and kept waiting. Thereafter, the processing targetwafer W is delivered from the Bernoulli chuck 280 to the porous chuck240 and suction-held.

After the processing target wafer W is suction-held on the porous chuck240, the porous chuck 240 is lowered to a predetermined position.Subsequently, the cleaning solution nozzle 253 at the waiting section255 is moved by the arm 251 to above the central portion of theprocessing target wafer W. Then, while the processing target wafer W isbeing rotated by the porous chuck 240, the cleaning solution is suppliedfrom the cleaning solution nozzle 253 to the joint surface W_(J) of theprocessing target wafer W. The supplied cleaning solution is diffusedover the entire surface of the joint surface W_(J) of the processingtarget wafer W by the centrifugal force to clean the joint surface W_(J)of the processing target wafer W (step A5 in FIG. 18).

Here, the plurality of superposed wafers T transferred in thetransfer-in/out station 2 have been subjected to inspection in advanceas described above and discriminated between a superposed wafer Tincluding a normal processing target wafer W and a superposed wafer Tincluding a defective processing target wafer W.

The normal processing target wafer W separated from the normalsuperposed wafer T is cleaned at its joint surface W_(J) in step A5 andthen transferred by the third transfer apparatus 41 to the inspectionapparatus 7. Note that the transfer of the processing target wafer W bythe third transfer apparatus 41 is substantially the same as theabove-described transfer of the processing target wafer W by the secondtransfer apparatus 32, and therefore the description thereof is omitted.

The inspection apparatus 7 inspects the presence or absence of a residueof the adhesive G on the joint surface W_(J) of the processing targetwafer W (step A6 in FIG. 18). If a residue of the adhesive G isconfirmed in the inspection apparatus 7, the processing target wafer Wis transferred by the third transfer apparatus 41 to the joint surfacecleaning unit 8 a in the post-inspection cleaning apparatus 8, and thejoint surface W_(J) is cleaned in the joint surface cleaning unit 8 a(step A7 in FIG. 18). After the joint surface W_(J) is cleaned, theprocessing target wafer W is transferred by the third transfer apparatus41 to the reversing unit 8 c and reversed in the vertical direction inthe reversing unit 8 c. Note that if any residue of the adhesive G isnot confirmed, the processing target wafer W is reversed in thereversing unit 8 c without being transferred to the joint surfacecleaning unit 8 a (step A8 in FIG. 18).

Thereafter, the reversed processing target wafer W is transferred by thethird transfer apparatus 41 again to the inspection apparatus 7 andsubjected to inspection of the non-joint surface W_(N) (step A9 in FIG.18). If a residue of the adhesive G is confirmed on the non-jointsurface W_(N), the processing target wafer W is transferred by the thirdtransfer apparatus 41 to the non-joint surface cleaning unit 8 b, andthe non-joint surface W_(N) is cleaned (step A10 in FIG. 18). Then, theprocessing target wafer W is transferred by the third transfer apparatus41 to the post-processing station 4. Note that if any residue of theadhesive G is not confirmed in the inspection apparatus 7, theprocessing target wafer W is transferred as it is to the post-processingstation 4 without being transferred to the non-joint surface cleaningunit 8 b.

Thereafter, predetermined post-processing is performed on the processingtarget wafer W in the post-processing station 4 (step A11 in FIG. 18).In this manner, the processing target wafer W becomes a product.

On the other hand, the defective processing target wafer W separatedfrom the defective superposed wafer T is cleaned at its joint surfaceW_(J) in step A5 and then transferred by the first transfer apparatus 20to the transfer-in/out station 2. Thereafter, the defective processingtarget wafer W is transferred from the transfer-in/out station 2 to theoutside and collected (step A12 in FIG. 18).

While the above-described steps A5 to A12 are being performed on theprocessing target wafer W, the supporting wafer S separated in theseparation apparatus 30 is transferred by the first transfer apparatus20 to the second cleaning apparatus 33. Then, in the second cleaningapparatus 33, the joint surface S_(J) of the supporting wafer S iscleaned (step A13 in FIG. 18). Note that the cleaning of the supportingwafer S in the second cleaning apparatus 33 is the same as theabove-described cleaning of the processing target wafer W in the firstcleaning apparatus 31, and therefore the description thereof is omitted.

Thereafter, the supporting wafer S whose joint surface S_(J) has beencleaned is transferred by the first transfer apparatus 20 to thetransfer-in/out station 2. Then, the supporting wafer S is transferredfrom the transfer-in/out station 2 to the outside and collected (stepA14 in FIG. 18). Thus, a series of separation processing of theprocessing target wafer W and the supporting wafer S ends.

According to the above embodiment, the inert gas is supplied from thegas supply pipe 125 to the processing space 112 and the inert gas isalso supplied from the gas supply pipe 191 to the processing space 112via the waiting space 218 in step A1. In addition, the processing space112 is covered with the first cover 200 and the second cover 201 and thewaiting space 218 is covered with the third cover 202 so that the gasflow of the inert gas flowing through the inside of the processing space112 and the waiting space 218 toward the opening 220 is formed. Thus,after a lapse of a predetermined period from the start of the supply ofthe inert gas, the inside of the processing space 112 can be filled withthe inert gas and the atmosphere inside the processing space 112 can bemaintained at a low oxygen concentration. Accordingly, the oxidation ofthe non-joint surface W_(N) of the processing target wafer W can besuppressed in step A1. In addition, in step A1, the superposed wafer Tis disposed at a position where it is not in contact with any of thefirst holding unit 110 and the second holding unit 111, so that theprocessing target wafer W is never heated. Accordingly, the oxidation ofthe non-joint surface W_(N) of the processing target wafer W can befurther suppressed.

Furthermore, by maintaining the atmosphere inside the processing space112 at a low oxidation concentration in step A1 as described above, theatmosphere inside the processing space 112 can be maintained at a lowoxygen concentration also in subsequent steps A2 and A3. Accordingly,the oxidation of the joint surface W_(J) of the processing target waferW can be suppressed.

When the first holding unit 110 holds the processing target wafer W insteps A2 and A3, the inert gas is supplied to the outer peripheralportion of the first holding unit 110 from the porous ring 130 formedwith the plurality of pores. This makes it possible to supply only theinert gas to the gap between the holding surface 121 a of the firstholding unit 110 and the non-joint surface W_(N) of the processingtarget wafer W as described above. Accordingly, the oxidation of thenon-joint surface W_(N) of the processing target wafer W which has beensubjected to heat treatment can be suppressed.

Moreover, the diameter of the holding surface 121 a of the porous 121 inthe first holding unit 110 is smaller than the diameter of theprocessing target wafer W, so that even when the adhesive G heated instep A3 flows around to the non-joint surface W_(N) at the edge portionof the processing target wafer W, the adhesive G stays in the groovepart 122 and never adheres to the porous 121. This makes it possible toprevent the processing target wafer W from being fixed to the porous121, and appropriately deliver the processing target wafer W from thefirst holding unit 110 to the Bernoulli chuck 280 in step A4.

In addition, the inert gas from the porous ring 130 can be horizontallysupply to the groove part 122 formed between the first holding unit 110and the processing target wafer W, thereby forming an inert gasatmosphere in the groove part 122. Accordingly, it is possible to moresurely supply only the inert gas to the gap between the holding surface121 a of the first holding unit 110 and the non-joint surface W_(N) ofthe processing target wafer W to further suppress the oxidation of thenon-joint surface W_(N) of the processing target wafer W which has beensubjected to heat treatment.

Further, the inert gas is supplied from the porous plate 190 to thejoint surface W_(J) of the processing target wafer W which has beenexposed due to the movement of the second holding unit 111 in thehorizontal direction by the moving mechanism 170 in step A3, therebyforming an inert gas atmosphere around the joint surface W_(J) of theprocessing target wafer W which has been exposed due to separation.Accordingly, the oxidation of the joint surface W_(J) of the heatedprocessing target wafer W can be suppressed.

Further, since the porous plate 190 has a size capable of covering theprocessing target wafer W, the inert gas can be supplied to the entiresurface of the joint surface W_(J) of the separated processing targetwafer W. Accordingly, the oxidation of the entire surface of theprocessing target wafer W can be suppressed.

Further, since the hollow portion 190 a which is hollowed in a recessshape along the shape of the processing target wafer W in a plan view isformed at the end portion in the moving direction of the porous plate190, the porous plate 190 can be disposed at a position where the porousplate 190 comes into contact with the processing target wafer W in aplan view. This makes it possible to instantly supply the inert gas tothe joint surface W_(J) of the processing target wafer W which has beenexposed due to the movement of the moving mechanism 170. Morespecifically, when the first holding unit 110 and the second holdingunit 111 are relatively moved in the horizontal direction by the movingmechanism 170, the joint surface W_(J) of the processing target wafer Wis exposed in a falcate shape (a range indicated with diagonal lines inFIG. 30) as illustrated in FIG. 30. In this case, by forming the hollowportion 190 a in the porous plate 190 and arranging the porous plate 190in a manner that the hollow portion 190 a is in contact with theprocessing target wafer W in a plan view, the entire surface of theexposed portion in the falcate shape can be covered with the porousplate 190. Accordingly, the inert gas can be instantly supplied to theentire surface of the exposed joint surface W_(J). Incidentally, thatthe hollow portion 190 a is in contact with the outer peripheral portionof the processing target wafer W in a plan view does not mean that thecircumference of the hollow portion 190 a is entirely in contact withthe outer peripheral portion of the processing target wafer W becausethe diameter of an arc of a circle of the hollow portion 190 a coincideswith the diameter of the processing target wafer W, but means that whenthe joint surface W_(J) of the processing target wafer W is exposed dueto separation, the hollow portion 190 a of the porous plate 190 is closeto the outer peripheral portion of the processing target wafer W in aplan view to a degree at which the joint surface W_(J) is covered withthe inert gas atmosphere above the porous plate 190 without beingexposed to the atmosphere in the processing container 100.

Further, in step A4, to the processing target wafer W held by theBernoulli chuck 280, the inert gas is supplied from the Bernoulli chuck280 to the joint surface W_(J) and the inert gas is supplied from thegas supply pipe 125 to the non-joint surface W_(N). Then, the processingtarget wafer W is cooled to the predetermined temperature, so that theoxidation does not proceed thereafter at the joint surface W_(J) and thenon-joint surface W_(N) of the processing target wafer W. In addition,what is used for cooling the processing target wafer W is the inert gas,so that the oxidation of the joint surface W_(J) and the non-jointsurface W_(N) of the processing target wafer W can be prevented alsoduring the cooling.

In the separation apparatus 30 in the above embodiment, an ion gassupply pipe 400 may be connected to the third cover 202 as illustratedin FIG. 31. The ion gas supply pipe 400 is provided with an ionizer 401that ionizes, for example, a nitrogen gas as the inert gas. For example,in steps A1 to A3, the ionized inert gas is supplied from the ion gassupply pipe 400 into the waiting space 218, flows through the inside ofthe waiting space 218 and the processing space 112 in sequence, and isthen exhausted from the opening 220. Note that the inert gas is notlimited to the nitrogen gas in this embodiment but may be any gas aslong as it contains no oxygen atom.

In this case, when the processing target wafer W and the supportingwafer S are separated from each other in step A3, separationelectrification of the processing target wafer W can be neutralized bythe ionized inert gas. In short, the damage to the processing targetwafer W due to static electricity can be prevented. Further, bysupplying the ionized inert gas from the ion gas supply pipe 400 intothe waiting space 218, the gas flow of the inert gas flowing toward theopening 220 in the waiting space 218 and the processing space 112 can bemore surely formed. Accordingly, the oxidation of the surface of theprocessing target wafer W in the processing space 112 can be furthersuppressed.

Note that the ion gas supply pipe 400 is connected to the ceiling part215 of the third cover 202 in the illustrated example, but may beconnected, for example, to the side wall part 216 of the third cover 202at the end portion opposite to the opening in the of the third cover202.

Though the silicon carbide is used for each of the porous ring 130 andthe porous plate 190 in the above embodiment, materials of them are notlimited to this embodiment. For example, Teflon (registered trademark)or the like may be used as long as the porous ring 130 and the porousplate 190 are formed with a plurality of fine pores that never involvesurrounding air when supplying the inert gas.

Further, though the distance L between the porous plate 190 and thejoint surface W_(J) of the processing target wafer W is set to 2 mm inthe above embodiment, the porous plate 190 can appropriately supply theinert gas to the joint surface W_(J) of the processing target wafer W topreferably suppress the proceed of rapid oxidation as long as thedistance L falls within a range of 0.5 mm to 4 mm.

Note that the porous plate 190 is disposed in parallel with the jointsurface W_(J) of the processing target wafer W in the above embodimentbut does not always have to be parallel with the joint surface W_(J) ofthe processing target wafer W. The porous plate 190 may be provided tobe inclined with respect to the joint surface W_(J) as long as thedistance L between the porous plate 190 and the joint surface W_(J) ismaintained between 0.5 mm and 4 mm.

Furthermore, the inert gas supply sources 127, 132, 195 are separatelyprovided in the separation apparatus 30 in the above embodiment, but acommon inert gas supply source may be provided.

The second holding unit 111 is moved in the horizontal direction withrespect to the first holding unit 110 in step A3 in the aboveembodiment, but the second holding unit 111 may be moved, for example,100 μm in the vertical direction in addition to the movement in thehorizontal direction. For example, the moving distance in the horizontaldirection of the second holding unit 111 is 300 mm, the thickness of theadhesive G in the superposed wafer T is, for example, 30 μm to 40 μm,and the height of the devices (bumps) formed on the joint surface W_(J)of the processing target wafer W is, for example, 20 μm in thisembodiment. In this case, the distance between the devices on theprocessing target wafer W and the supporting wafer S is minute. Hence,for example, when the second holding unit 111 is moved only in thehorizontal direction, the devices and the supporting wafer S can comeinto contact with each other, whereby the devices may be damaged.Accordingly, moving the second holding unit 111 in the horizontaldirection and also in the vertical direction can prevent the contactbetween the devices and the supporting wafer S to suppress the damage tothe devices. Note that the ratio between the moving distance in thevertical direction and the moving distance in the horizontal directionof the second holding unit 111 is arbitrarily set based on the height ofthe devices (bumps) on the processing target wafer W but not limited tothis embodiment.

Note that the first holding unit 110 may be moved in place of the secondholding unit 111. Also in this case, the first holding unit 110 may bemoved in the vertical direction and the horizontal direction.Alternatively, both of the first holding unit 110 and the second holdingunit 111 may be moved in the vertical direction and the horizontaldirection. Note that the porous plate 190 is only necessary to beconfigured to move in the horizontal direction relative to theprocessing target wafer W held by the first holding unit 110, namely,the object to which the inert gas is to be supplied even when either theholding unit 110 or 111 is moved, and its moving method and supportingmethod can be arbitrarily set. For example, when the first holding unit110 is moved in the horizontal direction, the porous plate 190 may besupported on the ceiling surface of the processing container 100 orsupported on the bottom surface of the processing container 100. Ineither case, by moving the processing target wafer W in the horizontaldirection above the porous plate 190 in a state that the processingtarget wafer W is distanced from the porous plate 190 by thepredetermined distance L, the atmosphere around the exposed jointsurface W_(J) of the processing target wafer W can be made the inertgas.

Further, instead of moving the second holding unit 111 in the verticaldirection and the horizontal direction in step A3, the second holdingunit 111 may be moved only in the horizontal direction and the movingspeed of the second holding unit 111 may be changed. Specifically, themoving speed at the time to start the movement of the second holdingunit 111 may be set to a low speed, and the moving speed may be thengradually increased. More specifically, since the joint area between theprocessing target wafer W and the supporting wafer S is large and thedevices on the processing target wafer W are likely to be affected bythe adhesive G at the time to start the movement of the second holdingunit 111, the moving speed of the second holding unit 111 is set to alow speed. Since the devices on the processing target wafer W becomemore unlikely affected by the adhesive G as the joint area between theprocessing target wafer W and the supporting wafer S becomes smaller,the moving speed of the second holding unit 111 is then graduallyincreased. Also in this case, it is possible to prevent the contactbetween the devices and the supporting wafer S to suppress the damage tothe devices.

Note that though the processing target wafer W and the supporting waferS are separated from each other with the processing target wafer Warranged on the upper side and the supporting wafer S arranged on thelower side in the above embodiment, the upper and lower arrangement ofthe processing target wafer W and the supporting wafer S may bereversed.

Further, a heating device, for example, a heater for heating the inertgas to be supplied to the processing space 112 and the waiting space 218may be provided in the separation apparatus 30. Alternatively, the inertgas to be supplied from the gas supply pipes 125, 191 may be heated inadvance. In addition, the inert gas at substantially the sametemperature (for example, 200° C.) as those of the first holding unit110 and the second holding unit 111 may be supplied to the processingspace 112 and the waiting space 218. With the above configuration, thesoftened state of the adhesive G can be maintained without cooling ofthe superposed wafer T by the inert gas. Further, the supply of theheated inert gas prevents the superposed wafer T from being partiallycooled to partially contract, resulting in no damage to the electroniccircuits on the processing target wafer W.

Note that as a concrete method of heating the inert gas, a heater 450 isprovided at the lower surface of the distribution plate 193 in theporous plate 190 as illustrated in FIG. 32. The heater 450 is, forexample, a film-shaped heater. A pressing plate 451 for pressing theheater 450 is disposed at the lower portion of the heater 450 so thatthe heater 450 is sandwiched between the distribution plate 193 and thepressing plate 451. Further, it is preferable to use materials whoseexpansion amounts at heating are substantially the same, for the porousplate 190, the distribution plate 193 and the pressing plate 451. All ofthem may be produced of, for example, the same material or may beproduced of porous carbon that is a porous material and a metal, forexample, titanium or the like, whose expansion amount is substantiallythe same as that of the porous carbon. Note that the heater is providedas the heating device also in the first holding unit 110, and the heateris the same as the above-described heater 450 and description thereofwill be omitted.

Further, a monitoring device 500 for monitoring pore clogging of theplurality of pores in the porous plate 190 may be provided asillustrated in FIG. 33 and FIG. 34. The monitoring device 500 iscomposed of a plurality of through holes 501 provided in the porousplate 190, pipes 502 each having one end connected to the through hole501, and pressure gauges 503 each disposed in the middle of the pipe502. Note that the other end of the pipe 502 is opened. The diameter ofthe through hole 501 is preferably small, and is set to, for example, 1mm. The through holes 501 are provided at regular intervals on linessimilar to the end portion of the hollow portion 190 a and arranged in aplurality of rows. Note that an inner surface 504 of the through hole501 is sealed by coating treatment.

Further, the pressure gauge 503 is provided for each of the plurality ofthrough holes 501 to detect the pressure, and when the pressure becomeslower than a predetermined value, it is considered that pore clogginghas occurred also in a portion of the porous plate 190 near the thoughhole 501, and warning is issued. Then, the separation processing isstopped and cleaning operation is performed. This can prevent poreclogging in the porous plate 190 and can evenly jet the inert gas fromthe porous plate 190 at all times.

Note that though the pressure difference with respect to the inside ofthe room is monitored by the pressure gauge 503 in the above embodiment,a suction pump (not illustrated) may be connected to the other end ofthe pipe 502 so that an absolute pressure is monitored by the pressuregauge 503.

Note that parts of the above embodiments may be combined andimplemented, and the same operation and effect can be obtained.

Preferred embodiments of the present invention have been described abovewith reference to the accompanying drawings, but the present inventionis not limited to the embodiments. It should be understood that variouschanges and modifications are readily apparent to those skilled in theart within the scope of the technical spirit as set forth in claims, andthose should also be covered by the technical scope of the presentinvention. The present invention is not limited to the embodiments butcan take various forms. The present invention is also applicable to thecase where the substrate is a substrate other than the wafer, such as anFPD (Flat Panel Display), a mask reticle for a photomask or the like.

EXPLANATION OF CODES

-   1 separation system-   30 separation apparatus-   32 second transfer apparatus-   110 first holding unit-   111 second holding unit-   112 processing space-   121 porous-   121 a holding surface-   124 suction pipe-   125 gas supply pipe-   128 heating mechanism-   130 porous ring-   151 heating mechanism-   160 raising and lowering mechanism-   170 moving mechanism-   190 porous plate-   190 a hollow portion-   200 first cover-   201 second cover-   202 third cover-   218 waiting space-   220 opening-   280 Bernoulli chuck-   290 gas jetting ports-   300 control unit-   400 ion gas supply pipe-   401 ionizer-   450 heater-   500 monitoring device-   G adhesive-   S supporting wafer-   T superposed wafer-   W processing target wafer-   W_(J) joint surface-   W_(N) non-joint surface

What is claimed is:
 1. A separation method of separating a superposedsubstrate in which a processing target substrate and a supportingsubstrate are joined together with an adhesive, into the processingtarget substrate and the supporting substrate using a separationapparatus, the separation apparatus comprising: a first holding unitthat includes a heating mechanism for heating the processing targetsubstrate and holds the processing target substrate; a second holdingunit that includes a heating mechanism for heating the supportingsubstrate and holds the supporting substrate; a raising and loweringmechanism that raises and lowers the superposed substrate in a verticaldirection between the first holding unit and the second holding unit; amoving mechanism that moves the first holding unit and/or the secondholding unit in the vertical direction and a horizontal direction; a gassupply part that supplies an inert gas into a processing space betweenthe first holding unit and the second holding unit; a porous plate ofporous material that has a plurality of pores, the porous plate having aflat plate shape, the flat plate shape is adapted to cover theprocessing target substrate in a plan view, the porous plate supplies,via the plurality of pores, the inert gas to a joint surface of theprocessing target substrate, the joint surface is exposed by moving thefirst holding unit and the second holding unit in the horizontaldirection by the moving mechanism; a flow space between the firstholding unit and the porous plate, the flow space covers an entire planeof a planar surface of the porous plate in the plan view, the flow spaceevenly supplies the inert gas to the entire plane of the planar surfaceof the porous plate in the plan view, wherein the gas supply partcommunicates the inert gas from a gas supply source to the flow space,and the flow space evenly communicates the inert gas from the gas supplypart to the entire plane of the planar surface of the porous plate, andthe porous plate communicates the inert gas evenly through the entireplane of the planar surface of the porous plate to a planar surface ofthe processing target substrate held by the first holding unit; and aporous ring, the porous ring is annularly provided along an outerperipheral portion of the first holding unit, the porous ring is spacedapart in the horizontal direction from the porous plate, the porous ringsupplies the inert gas in the horizontal direction from the outerperipheral portion of the first holding unit toward the processing spacebetween the first holding unit and the second holding unit, theseparation method comprising: a first step of disposing the superposedsubstrate by the raising and lowering mechanism at a position where thesuperposed substrate is not in contact with the first holding unit andthe second holding unit in the processing space between the firstholding unit and the second holding unit, and supplying the inert gasfrom the gas supply part into the processing space; a second step ofthereafter moving the first holding unit and the second holding unit inthe vertical direction by the moving mechanism, and holding theprocessing target substrate by the first holding unit and holding thesupporting substrate by the second holding unit; and a third step ofthereafter moving the first holding unit and the second holding unit inthe horizontal direction by the moving mechanism while heating theprocessing target substrate held by the first holding unit and thesupporting substrate held by the second holding unit, to separate theprocessing target substrate and the supporting substrate from eachother, wherein, in the third step, the porous plate supplies the inertgas from the porous plate to the joint surface of the processing targetsubstrate exposed by the separation, the porous plate being distancedfrom the joint surface of the processing target substrate by apredetermined distance in the vertical direction.
 2. The separationmethod according to claim 1, wherein the first holding unit is providedwith the gas supply part and a suction part that sucks the processingtarget substrate to suction-hold the processing target substrate, andwherein in the second step, the supply of the inert gas from the gassupply part is stopped, and suction from the suction part is performedto hold the processing target substrate by the first holding unit. 3.The separation method according to claim 1, wherein a hollow portionhollowed in a recess shape along a shape of the processing targetsubstrate in a plan view is formed at an end portion in a movingdirection of the porous plate, and wherein at least in the first step orthe second step, the porous plate is disposed such that the hollowportion thereof is in contact with the processing target substrate in aplan view, and the inert gas is supplied from the porous plate to theprocessing space between the first holding unit and the second holdingunit.
 4. The separation method according to claim 1, wherein in thethird step, the moving mechanism moves the porous plate in thehorizontal direction in synchronization with the second holding unit. 5.The separation method according to claim 1, wherein the first holdingunit and the second holding unit are provided with a first cover and asecond cover respectively that are provided to cover the processingspace between the first holding unit and the second holding unit,wherein the first cover is provided with a third over that is providedto cover the porous plate, wherein end portions of the first cover andthe second cover in a moving direction of the first holding unit or thesecond holding unit are opened, wherein an end portion of the thirdsecond cover in a moving direction of the porous plate is opened, andwherein an atmosphere in a space surrounded by the first cover, thesecond cover, and the third cover is exhausted from an opening formed atthe first cover and the second cover on an opposite side to the thirdcover.
 6. The separation method according to claim 5, wherein the thirdcover is provided with an ionized gas supply part for supplying an inertgas ionized by an ionizer into the third cover, and wherein at least inthe first step, the second step, or the third step, the inert gasionized by the ionizer is supplied from the ionized gas supply part intothe third cover.
 7. The separation method according to claim 1, whereinthe separation apparatus has a porous part annularly provided along anouter peripheral portion of the first holding unit and formed with aplurality of pores, for supplying an inert gas to the outer peripheralportion of the first holding unit holding the processing targetsubstrate, and wherein at least in the second step or the third step,the inert gas is supplied from the porous part to the outer peripheralportion of the first holding unit.
 8. The separation method according toclaim 1, further comprising: after the third step, a fourth step ofdelivering the processing target substrate from the first holding unitto a Bernoulli chuck and cooling the processing target substrate held bythe Bernoulli chuck.
 9. The separation method according to claim 8,wherein in the fourth step, the Bernoulli chuck jets an inert gas tohold the processing target substrate.
 10. The separation methodaccording to claim 8, wherein in the fourth step, the inert gas issupplied from the gas supply part to the processing target substrateheld by the Bernoulli chuck.
 11. The separation method according toclaim 1, wherein the first holding unit has a porous body formed with aplurality of pores and coming into contact with the processing targetsubstrate to suction-hold the processing target substrate, and wherein adiameter of a holding surface of the porous body that holds theprocessing target substrate is smaller than a diameter of the processingtarget substrate.
 12. The separation method according to claim 1,wherein the inert gas supplied from the porous plate has been heated.13. A separation apparatus for separating a superposed substrate inwhich a processing target substrate and a supporting substrate arejoined together with an adhesive, into the processing target substrateand the supporting substrate, the separation apparatus comprising: afirst holding unit that includes a heating mechanism for heating theprocessing target substrate, the first holding unit holds the processingtarget substrate; a second holding unit that includes a heatingmechanism for heating the supporting substrate, the second holding unitholds the supporting substrate; a raising and lowering mechanism thatraises and lowers the superposed substrate in a vertical directionbetween the first holding unit and the second holding unit; a movingmechanism that moves the first holding unit and/or the second holdingunit in the vertical direction and a horizontal direction; a gas supplypart that supplies an inert gas into a processing space between thefirst holding unit and the second holding unit; a porous plate of porousmaterial that has a plurality of pores, the porous plate having a flatplate shape, the flat plate shape is adapted to cover the processingtarget substrate in a plan view, the porous plate supplies, via theplurality of pores, the inert gas to a joint surface of the processingtarget substrate, the joint surface is exposed by moving the firstholding unit and the second holding unit in the horizontal direction bythe moving mechanism; a flow space between the first holding unit andthe porous plate, the flow space covers an entire plane of a planarsurface of the porous plate in the plan view, the flow space evenlysupplies the inert gas to the entire plane of the planar surface of theporous plate in the plan view, wherein the gas supply part communicatesthe inert gas from a gas supply source to the flow space, and the flowspace evenly communicates the inert gas from the gas supply part to theentire plane of the planar surface of the porous plate, and the porousplate communicates the inert gas evenly through the entire plane of theplanar surface of the porous plate to a planar surface of the processingtarget substrate held by the first holding unit; a control unitconfigured to control the raising and lowering mechanism, the movingmechanism, and the gas supply part to execute: a first step of disposingthe superposed substrate by the raising and lowering mechanism at aposition where the superposed substrate is not in contact with the firstholding unit and the second holding unit in the processing space betweenthe first holding unit and the second holding unit, and supplying theinert gas from the gas supply part into the processing space; a secondstep of thereafter moving the first holding unit and the second holdingunit in the vertical direction by the moving mechanism, and holding theprocessing target substrate by the first holding unit and holding thesupporting substrate by the second holding unit; and a third step ofthereafter moving the first holding unit and the second holding unit inthe horizontal direction by the moving mechanism while heating theprocessing target substrate held by the first holding unit and thesupporting substrate held by the second holding unit, to separate theprocessing target substrate and the supporting substrate from eachother; and a porous ring, the porous ring is annularly provided along anouter peripheral portion of the first holding unit, the porous ring isspaced apart in the horizontal direction from the porous plate, theporous ring supplies the inert gas in the horizontal direction from theouter peripheral portion of the first holding unit toward the processingspace between the first holding unit and the second holding unit,wherein the control unit is further configured to control, in the thirdstep, the porous plate to supply the inert gas from the porous plate tothe joint surface of the processing target substrate exposed by theseparation, the porous plate being distanced from the joint surface ofthe processing target substrate by a predetermined distance in thevertical direction.
 14. The separation apparatus according to claim 13,wherein the first holding unit is provided with the gas supply part anda suction part that sucks the processing target substrate tosuction-hold the processing target substrate, and wherein the controlunit is further configured to control, in the second step, the gassupply part and the suction part to stop the supply of the inert gasfrom the gas supply part, and to perform suction from the suction partto hold the processing target substrate by the first holding unit. 15.The separation apparatus according to claim 13, wherein, in the planview, a concave portion is defined which is semicircular conforming to ashape of the processing target substrate, the concave portion beingformed at an end portion of the porous plate, the end portion beingdisposed in a moving direction of the porous plate, and wherein thecontrol unit is further configured to control, at least in the firststep or the second step, the porous plate to supply the inert gas fromthe porous plate to the processing space between the first holding unitand the second holding unit, the porous plate being disposed such thatthe concave portion thereof is in contact with the processing targetsubstrate in a plan view.
 16. The separation apparatus according toclaim 13, further comprising: a porous part annularly provided along anouter peripheral portion of the first holding unit and formed with aplurality of pores, for supplying an inert gas to the outer peripheralportion of the first holding unit holding the processing targetsubstrate, and wherein the control unit is further configured tocontrol, at least in the second step or the third step, the porous partto supply the inert gas from the porous part to the outer peripheralportion of the first holding unit.
 17. The separation apparatusaccording to claim 13, wherein the porous plate is provided with aheating device for heating the inert gas to be supplied from the porousplate.
 18. A separation system comprising a separation apparatus forseparating a superposed substrate in which a processing target substrateand a supporting substrate are joined together with an adhesive, intothe processing target substrate and the supporting substrate, theseparation apparatus comprising: a first holding unit that includes aheating mechanism for heating the processing target substrate, the firstholding unit holds the processing target substrate; a second holdingunit that includes a heating mechanism for heating the supportingsubstrate, the second holding unit holds the supporting substrate; araising and lowering mechanism that raises and lowers the superposedsubstrate in a vertical direction between the first holding unit and thesecond holding unit; a moving mechanism that moves the first holdingunit and/or the second holding unit in the vertical direction and ahorizontal direction; a gas supply part that supplies an inert gas intoa processing space between the first holding unit and the second holdingunit; a porous plate of porous material that has a plurality of pores,the porous plate having a flat plate shape, the flat plate shape isadapted to cover the processing target substrate in a plan view, theporous plate supplies, via the plurality of pores, the inert gas to ajoint surface of the processing target substrate, the joint surface isexposed by moving the first holding unit and the second holding unit inthe horizontal direction by the moving mechanism; a flow space betweenthe first holding unit and the porous plate, the flow space covers anentire plane of a planar surface of the porous plate in the plan view,the flow space evenly supplies the inert gas to the entire plane of theplanar surface of the porous plate in the plan view, wherein the gassupply part communicates the inert gas from a gas supply source to theflow space, and the flow space evenly communicates the inert gas fromthe gas supply part to the entire plane of the planar surface of theporous plate, and the porous plate communicates the inert gas evenlythrough the entire plane of the planar surface of the porous plate to aplanar surface of the processing target substrate held by the firstholding unit; a control unit configured to control the raising andlowering mechanism, the moving mechanism, and the gas supply part toexecute: a first step of disposing the superposed substrate by theraising and lowering mechanism at a position where the superposedsubstrate is not in contact with the first holding unit and the secondholding unit in the processing space between the first holding unit andthe second holding unit, and supplying the inert gas from the gas supplypart into the processing space; a second step of thereafter moving thefirst holding unit and the second holding unit in the vertical directionby the moving mechanism, and holding the processing target substrate bythe first holding unit and holding the supporting substrate by thesecond holding unit; and a third step of thereafter moving the firstholding unit and the second holding unit in the horizontal direction bythe moving mechanism while heating the processing target substrate heldby the first holding unit and the supporting substrate held by thesecond holding unit, to separate the processing target substrate and thesupporting substrate from each other; and a porous ring, the porous ringis annularly provided along an outer peripheral portion of the firstholding unit, the porous ring is spaced apart in the horizontaldirection from the porous plate, the porous ring supplies the inert gasin the horizontal direction from the outer peripheral portion of thefirst holding unit toward the processing space between the first holdingunit and the second holding unit, the separation system comprising atransfer apparatus that transfers the processing target substrateseparated in the separation apparatus, wherein the transfer apparatushas a Bernoulli chuck for jetting an inert gas to hold the processingtarget substrate, wherein the control unit is further configured tocontrol, in the third step, the porous plate to supply the inert gasfrom the porous plate to the joint surface of the processing targetsubstrate exposed by the separation, the porous plate being distancedfrom the joint surface of the processing target substrate by apredetermined distance in the vertical direction, and wherein thecontrol unit is further configured to control, after the third step, theBernoulli chuck to execute a fourth step of cooling the processingtarget substrate delivered from the first holding unit to the Bernoullichuck by supplying the inert gas from the Bernoulli chuck to theprocessing target substrate.